When you try to open the app, it shows the error message that " The program can't start because api-ms-win-crt-runtime-l1-1-0.dll is missing from your computer" as below:
The reason is that the Windows version is old and you need to download the Microsoft Visual C++ 2015 to fix the issue. Click here to get the downloading link.
When you try to open the app, it does not respond at all, it could be another software on your computer that blocks the ezTalks app. In that case, please send an email to email@example.com or submit a ticket here and we can remotely troubleshoot with you.